In-plane mems optical switch

Abstract

In-plane MEMS optical switch. An optical switch includes a first bus waveguide supported by a substrate, an optical antenna suspended over the first bus waveguide via a spring, and an interdigital electrode coupling the substrate with the optical antenna and configured to control an orientation of the optical antenna relative to the first bus waveguide. When a voltage difference applied to the interdigital electrode is less than a lower threshold, the optical antenna is in a first orientation offset from the first bus waveguide, when the voltage difference applied to the interdigital electrode is greater than an upper threshold, the optical antenna is in a second orientation offset from the first bus waveguide, and the offset at the second orientation is greater than the offset at the first orientation.

Description

[0001] Cross-referencing of related applications. Technical Field

[0002] This invention generally relates to systems and apparatus for guiding and transmitting optical signals. Background Technology

[0003] Lidar is considered a key driver of many new technologies, such as autonomous vehicles. Chip-based lidar (also known as solid-state lidar or on-chip lidar) is expected to be widely used in future autonomous vehicles. However, many challenges remain in creating practical chip-based lidar that meets the requirements of vehicle OEMs. One of these challenges is beam steering. Various methods have been developed to control the beam in chip-based lidar, such as micromirror arrays, optical phased arrays, wavelength tuning, and photonic crystal waveguides; however, these methods face challenges such as limited field of view, complex control electronics, and high requirements for the laser. Summary of the Invention

[0004] An optical switch includes: a first bus waveguide supported by a substrate, an optical antenna suspended above the first bus waveguide by a spring, and interdigitated electrodes coupling the substrate to the optical antenna and configured to control the orientation of the optical antenna relative to the first bus waveguide. When the voltage difference applied to the interdigitated electrodes is less than a lower threshold, the optical antenna is in a first orientation away from the first bus waveguide; when the voltage difference applied to the interdigitated electrodes is greater than an upper threshold, the optical antenna is in a second orientation away from the first bus waveguide, and the offset at the second orientation is greater than the offset at the first orientation.

[0005] An optical switch includes: a bus waveguide supported by a substrate, an optical antenna suspended above the bus waveguide by a spring, and interdigitated electrodes coupling the substrate to the optical antenna and configured to control the orientation of the optical antenna relative to the bus waveguide. When the voltage difference applied to the interdigitated electrodes is less than a lower threshold, the optical antenna is positioned at a first orientation relative to the bus waveguide; when the voltage difference applied to the interdigitated electrodes is greater than an upper threshold, the optical antenna is positioned at a second orientation relative to the bus waveguide, and the first orientation and the second orientation are separated by a predetermined distance.

[0006] A beam steering system includes a bus waveguide supported by a substrate, an optical antenna supported by springs at a distance above the bus waveguide, an interdigital electrode coupling the substrate to the optical antenna and configured to control an orientation of the optical antenna relative to the bus waveguide, an optical tree, and a lens. The optical tree has at least one type of optical switch, the optical tree configured to collect light from the optical antenna. The lens is spaced apart from the substrate and configured to diffract light onto the optical antenna. The optical antenna is positioned a first distance from the bus waveguide when a voltage difference applied to the interdigital electrode is less than a lower threshold, the optical antenna is positioned a second distance from the bus waveguide when the voltage difference applied to the interdigital electrode is greater than an upper threshold, and the second distance is less than the first distance. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a top view of an optical switch array system.

[0008] Figure 2 is a side view of an optical switch array system.

[0009] Figure 3 is a perspective view of a silicon photonic switch array.

[0010] Figure 4A is a top view of an optical switch in an optical switch array.

[0011] Figure 4B is a side view of an optical switch in an optical switch array in an OFF state.

[0012] Figure 4C is a side view of an optical switch in an optical switch array in an ON state.

[0013] Figure 5A is a perspective view of an optical switch in a switch array having a light coupling cantilever and a fixed optical antenna.

[0014] Figure 5B is a perspective view of a two-dimensional fixed optical antenna.

[0015] Figure 6 is a perspective view of a light coupling cantilever having a fixed optical antenna.

[0016] Figure 7A is a cross-sectional view of a light coupling cantilever of a MEMS switch of Figure 6 in an idle state.

[0017] Figure 7B is a cross-sectional view of a light coupling cantilever of a MEMS switch of Figure 6 in an actuated state.

[0018] Figure 7C is a cross-sectional view of a light coupling cantilever of a MEMS switch ofFigure 6 A cross-sectional view of a fixed optical antenna for a MEMS switch.

[0019] Figure 7D It is in an actuated state. Figure 6 A cross-sectional view of a fixed optical antenna for a MEMS switch.

[0020] Figure 8 This is a perspective view of an optical switch array system that transmits optical signals.

[0021] Figure 9 This is a perspective view of an optical switch array system that receives optical signals.

[0022] Figure 10 This is a perspective view of an optical switch array system that receives and transmits optical signals.

[0023] Figure 11 It is a perspective view of an optical switch array system that includes at least two types of optical switches.

[0024] Figure 12 It is a perspective view of an optical switch array system that includes a splitter tree and optical switches.

[0025] Figure 13 It is a perspective view of an optical switch array system that includes a branch tree and at least two types of optical switches.

[0026] Figure 14 This is a diagram of a switch array system configured to independently address rows and columns.

[0027] Figure 15 This is a diagram of a switch array system configured to simultaneously address subarrays.

[0028] Figure 16 It is a perspective view of the bus waveguide and the corresponding coupler waveguide.

[0029] Figure 17 It is a graphical representation of the coupled field distribution with respect to distance.

[0030] Figure 18 It is a series of two-dimensional graphical representations of the coupled field distribution with respect to the propagation distance.

[0031] Figure 19 It is a graphical representation of coupling efficiency with respect to the length of the coupling taper.

[0032] Figure 20 It is a graphical representation of transmission loss with respect to wavelength.

[0033] Figure 21 It is a graphical representation of energy loss with respect to the gap size.

[0034] Figure 22 is a graphical representation of the radiation pattern with respect to angle.

[0035] Figure 23 is a side view illustration of a waveguide grating versus free space angle.

[0036] Figure 24 is a perspective view of a cantilever spring biased by a voltage.

[0037] Figure 25 is a graphical representation of displacement along the Z axis versus switching speed.

[0038] Figure 26 is a top view of a switch array layout with individual elements detailed.

[0039] Figure 27A is a perspective view of a switch array with movable optical couplers on a suspended layer and fixed optical antennas on a substrate layer.

[0040] Figure 27B is a top view of a switch array with movable optical couplers on a suspended layer and fixed optical antennas on a substrate layer.

[0041] Figure 28A is a cross-sectional view of the movable optical coupler of Figure 27 in a closed orientation.

[0042] Figure 28B is a cross-sectional view of the movable optical coupler of Figure 27 in an open orientation.

[0043] Figure 29 is a top view of a switch array layout with movable optical couplers on a suspended layer and fixed optical antennas on a substrate layer with individual elements detailed.

[0044] Figure 30 is a top view of a switch array layout with movable optical couplers on a suspended layer and fixed optical antennas on a substrate layer with individual elements detailed.

[0045] Figure 31 is a top view of an element in a switch array layout with movable optical couplers on a suspended layer and fixed optical antennas on a substrate layer.

[0046] Figure 32 is a cross-sectional view of an element of Figure 31

[0047] Figure 33 is a graphical representation of the field distribution of a grating antenna with respect to X and Y coordinates.

[0048] Figure 34 is a perspective view illustrating displacement of an optical coupler.​

[0049] Figure 35 is a perspective view of a grating antenna illustrating a launch angle.

[0050] Figure 36 is a graphical representation of intensity versus launch angle.

[0051] Figure 37 is a side view of a mirror for compensating for a non-zero antenna launch angle.

[0052] Figure 38 is a side view of an optical prism for compensating for a non-zero antenna launch angle.

[0053] Figure 39 is a side view of a micro-prism array for compensating for a non-zero antenna launch angle.

[0054] Figure 40A is a top view of an antenna array with a shunt tree and switches.

[0055] Figure 40B is a top view of an antenna array with multiple switch types.

[0056] Figure 40C is a top view of an antenna array with a shunt tree and multiple switch types.

[0057] Figure 41A is a perspective view of a switch array with a movable grating that travels longitudinally with multiple stopping positions.

[0058] Figure 41B is a detailed perspective view of a movable grating that travels longitudinally with multiple stopping positions to a bus waveguide from Figure 41A .

[0059] Figure 41C is a perspective view of a switch array with a movable grating that travels longitudinally to a bus waveguide.

[0060] Figure 41D is a detailed perspective view of two movable gratings that travel longitudinally to a bus waveguide from Figure 41C .

[0061] Figure 41E is a top view of a movable grating that travels longitudinally to a bus waveguide via interdigitated electrodes.

[0062] Figure 42A is a perspective view of a switch array with a movable grating that travels laterally with multiple stopping positions to a bus waveguide.

[0063] Figure 42B This is a detailed perspective view of a movable grating, which has a perspective view from... Figure 41A The switch array travels laterally to the bus waveguide in the case of multiple stop positions.

[0064] Figure 42C This is a top view of a movable grating that travels laterally to the bus waveguide via interdigitated electrodes.

[0065] Figure 43 It is a perspective view of a switch array with a movable grating that travels laterally with in-plane and out-of-plane stopping orientations relative to the waveguide.

[0066] Figure 44 This is a perspective view of a switch that uses electrostatic levitation to control the coupling distance between the bus waveguide and the grating.

[0067] Figure 45A This is a perspective view of a switch with a comb driver used to control the coupling distance between the bus waveguide and the grating.

[0068] Figure 45B It is along Figure 45A A cross-sectional view of the cut, illustrating the comb-shaped actuator.

[0069] Figure 46 This is a cross-sectional view illustrating the packaged switch array system.

[0070] Figure 47 This is a perspective view of a dual-grating switch that travels laterally with its stop orientation in the plane of the waveguide.

[0071] Figure 48 This is a perspective view of a dual-grating switch that travels laterally with both in-plane and out-of-plane stopping orientations relative to the waveguide.

[0072] Figure 49 This is a perspective view of a bimorphic switch in which the grating is positioned in-plane.

[0073] Figure 50 This is a perspective view of a dual-mode switch with a vertically rotating grating in an out-of-plane orientation.

[0074] Figure 51 It is a perspective view of a switch array in which grating elements rotate about an axis perpendicular to the waveguide.

[0075] Figure 52 It is a perspective view of a switch array in which grating elements rotate around an axis parallel to the waveguide.

[0076] Figure 53This is a top view of the grating array on a rotating disk that uses a rotation mechanism to align in-plane and out-of-plane operations.

[0077] Figure 54A This is a cross-sectional view of a coupler waveguide with a bistable membrane in the closed orientation.

[0078] Figure 54B This is a cross-sectional view of a coupler waveguide with a bistable membrane in the open orientation. Detailed Implementation

[0079] Detailed embodiments of the invention are disclosed herein as needed; however, it should be understood that the disclosed embodiments are merely examples of the invention and may be embodied in various and alternative forms. The figures are not necessarily to scale; certain features may be exaggerated or minimized to show detail of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as teaching those skilled in the art to employ the representative basis of the invention in various ways.

[0080] The term "substantially" may be used herein to describe the disclosed or claimed embodiments. The term "substantially" may modify values ​​or relative characteristics disclosed or claimed in this disclosure. In such cases, "substantially" may mean that the value or relative characteristic it modifies is within ±0%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, or 10% of that value or relative characteristic.

[0081] Although different embodiments are illustrated in this application using silicon MEMS structures, the MEMS structure can be made of other MEMS materials, such as SiC and SiN.

[0082] This disclosure presents microelectromechanical systems (MEMS) switches, switch arrays, and systems including MEMS switches with coupler cantilever arms and multiple fixed optical antenna configurations. In various applications, such MEMS switches can be used to couple light from waveguides on a photonic integrated circuit (PIC) chip into free space.

[0083] LiDAR is a key enabler for many new systems, such as autonomous driving. Chip-based LiDAR (also known as solid-state LiDAR or on-chip LiDAR) promises widespread use in future autonomous vehicles due to its compact size and low cost. Nevertheless, many challenges remain in creating practical chip-based LiDAR that meets the requirements of OEMs. One of these challenges is beam control. Various methods have been developed to guide the beam in chip-based LiDAR, such as micromirror arrays, optical phased arrays, wavelength tuning, and photonic crystal waveguides. However, these methods face one or more challenges, such as limited field of view, complex control electronics, high requirements for lasers, and low technological maturity.

[0084] In addition to the methods mentioned above, optical amplitude arrays can also control the beam in a chip-based lidar system. Figure 1 This is a top view of the optical switch array system 100. The system 100 includes: a photonic integrated circuit (PIC) chip 102, multiple light sources / optical antennas 104, and a lens 106. Figure 2 This is a side view of an optical switch array system 200. System 200 includes: a photonic integrated circuit (PIC) chip 202, multiple light sources / optical antennas 204, and a lens 206.

[0085] like Figure 1 (Top view) and Figure 2 As shown in the side view, the optical amplitude array consists of an array of light sources or optical antennas (such as 104, 204, each of which can be considered a "pixel") and a lens or lens system (e.g., 106, 206) (for simplicity, "lens" will be used in the following description), wherein the optical pixel array is located at (or near) the focal plane of the lens. The amplitude of light emitted from each optical pixel can be 0 (no light emission) or 1 (full light emission). The emitted light from each optical pixel undergoes refraction as it passes through the lens and is deflected in a certain direction according to the laws of physical optics. By activating the optical pixels at different orientations, light can be controlled and directed in different directions in free space, thus achieving beam control. A two-dimensional (2D) arrangement of optical pixel arrays can achieve 2D beam control.

[0086] There are various ways to fabricate optical pixel arrays. For example, such arrays can be composed of light source arrays such as vertical external cavity surface-emitting lasers (VECSELs). Such arrays can also consist of waveguide arrays having an optical antenna array controlled by an optical switch array. In this disclosure, methods involving optical MEMS switch arrays configured to control light emission from optical antennas are explored.

[0087] This disclosure includes beam control enabled by a MEMS switch-based amplitude array. Such a MEMS switch-based amplitude array consists of a waveguide array having a MEMS switchable antenna located at or near the focal plane of a lens. Activating the optical antenna in different orientations allows the beam to be directed in different directions, such as… Figure 1 and Figure 2 As shown.

[0088] Compared to micromirror array-based beamforming, amplitude array beamforming can achieve a larger field of view. Compared to optical phased array beamforming, amplitude array beamforming requires much simpler control electronics. Compared to wavelength-tunable beamforming, amplitude array beamforming does not require large wavelength tunability of the laser source. Compared to photonic crystal waveguide-based beamforming, amplitude array beamforming is more direct and technically more stable.

[0089] There are many options for optical switches. The most common optical switches that can be used in amplitude array applications include micromirror-based switches, liquid crystal switches, and thermo-optical switches. Micromirror-based and liquid crystal switches have relatively large sizes, such as hundreds of micrometers, and require switching times in the millisecond range, making each pixel too large and too slow for chip-to-liDAR applications. On the other hand, thermo-optical switches have low extinction ratios and high insertion losses, which are also unfavorable for such applications. Optical switches based on MEMS structures can be compact and fast-switching, and have high extinction ratios, making this technology a good candidate for amplitude array applications.

[0090] Figure 3 This is a perspective view of a silicon photonic integrated switch (PIC) array 300. The array has an in-port 310, a through port 314, and a drop port 312, such that when a low-loss crossover 316 (such as an optical switch) is activated, light travels from the in-port 310 through the low-loss crossover 316 to the drop port 312. For light to travel from the in-port 310 to the low-loss crossover 316, a MEMS-driven thermally adiabatic coupler must be positioned at a certain distance from the bus waveguide. When the low-loss crossover 316 is not activated, light travels from the in-port 310 to the through port 314.

[0091] A close-up view of the optical switching elements of array 304 includes: a MEMS-driven thermally adiabatic coupler 318 and a bus waveguide 320. The diagram shows the optical switch in the off state 306, where light is transmitted from input 310 to output 314, with the cantilever coupler positioned at a distance 316 from the bus waveguide, resulting in a coupling efficiency of less than 1%. The diagram also shows the optical switch in the on state 308, where light is transmitted from input 310 to output 312, with the cantilever coupler 318 activated, allowing light from the bus waveguide to couple with output 312 with a coupling efficiency greater than 50%.

[0092] like Figure 3 As shown, this silicon photonic MEMS switch network employs two sets of orthogonal bus waveguides and MEMS-driven vertical thermally adiabatic couplers. The vertical gap distance can be controlled by MEMS electrostatic actuators and mechanical stoppers. In the off state, the thermally adiabatic couplers are located far above the waveguides, so light continues to propagate through the ports without interruption. In the on state, the thermally adiabatic couplers move towards the bus waveguides, and light couples to the thermally adiabatic couplers, and then outwards to the output ports through another thermally adiabatic coupler.

[0093] MEMS switches can be used to selectively couple light into and out of waveguides in optical transmitting / receiving terminals. In one embodiment, each optical switch can be implemented using a physically translational optical grating. In the off state, the translational optical grating is positioned sufficiently far above the bus waveguide, while in the on state, a MEMS actuator can move the translational optical grating down toward the bus waveguide to achieve effective optical coupling between the grating and the bus waveguide.

[0094] Figure 4A This is a top view of the optical switch 400. The optical switch 400 includes a grating 402, which includes a plurality of optical coupler elements 404, 406, 408 aligned with the bus waveguide 410. Figure 4B This is a side view of the optical switch 400 in the off state. Wave 412 travels along direction 414 in the bus waveguide 410. The bus waveguide is supported by substrate 416 and is in the off state. The grating 402 is located at a distance 418 above the bus waveguide 410, resulting in low coupling efficiency between the grating 402 and the bus waveguide 410, and the wave continues to propagate in the bus waveguide 410. Figure 4C This is a side view of the optical switch 400 in the on state. In this figure, the grating 402 is located at a distance of 420 on the bus waveguide 410, which makes the coupling efficiency between the grating 402 and the bus waveguide 410 high, and the wave is refracted 422 from the bus waveguide 410 into free space.

[0095] In this disclosure, several MEMS switch embodiments include MEMS switches with coupler cantilever and optical antenna. Figure 5A The illustration shows an array of such MEMS switches used in an optical terminal. Here, a grating is used as an optical antenna in one example to illustrate the concept; other optical antennas (e.g., Figure 5B This concept is also feasible.

[0096] Figure 5A This is a perspective view of an optical switch with an optically coupled cantilever and a fixed optical antenna in a switch array 500. The switch array 500 can be on a single substrate 502, or it can be configured as a multi-chip module, where multiple optical switches are monolithically integrated on a photonic integrated circuit (PIC) chip, which is then combined with other PIC chips to form an array system 500. The single-substrate photonic integrated circuit (PIC) chip 502 includes a bus waveguide configured to input light 504 and distribute light among multiple rows 510a, 510b, 510c and columns of optical switches. Here, the three rows are configured as a first row 510a, a second row 510b, and a third row 510c, with each row having three columns of optical switches 506.

[0097] Figure 5B This is a perspective view of a two-dimensional fixed optical antenna 550. The optical antenna includes a coupler cantilever 552 and an optical antenna having a length 554 and a width 556. The ratio of length 554 to width 556 can be substantially 3:1, 5:2, 2:1, or similar. In the case of a gap 558 between the optical antenna and the side, it can be substantially 0.2, 0.3, 0.4, 0.5, or 0.6 times the width 556. The optical antenna can be configured to output or receive light substantially along an angle in x-axis 560 and an angle in y-axis 562.

[0098] Figure 6This is a perspective view of a MEMS switch 600 having an optically coupled cantilever 614 and a fixed optical antenna 616. The MEMS switch 600 includes a substrate 602 (such as a silicon substrate) having an insulating layer 604 (such as silicon dioxide). On top of the insulating layer 604 is a structural layer 606, such as a silicon layer. Within the structural layer 606 are structures such as a bus waveguide 608, a MEMS actuation electrode 610, a MEMS spring 612, the coupling cantilever 614, and the optical antenna 616. In this embodiment, the coupling waveguide 614 moves or hinges based on MEMS principles. For example, the MEMS actuation electrode 610 can be configured to cooperate with a reactive electrode located near the coupling waveguide and between the MEMS spring 612 and the coupling waveguide 614. When a voltage difference less than a lower threshold is applied between the reactive electrode and the actuation electrode, the coupling waveguide is held at a first distance from the bus waveguide via electrostatic force. The lower threshold can be a low differential voltage, such as a low voltage around 0 volts or zero volts, such as -5, -4, -3, -2, -1, 1, 2, 3, 4, or 5 volts. Below this lower threshold, the coupling cantilever can remain stationary or may move slightly such that the coupling efficiency between the bus waveguide 608 and the optical antenna 616 via the coupling waveguide 614 is less than 1% (e.g., off). Similarly, when the voltage difference between the reactive electrode and the actuating electrode 610 is greater than the upper threshold, the coupling waveguide is held at a second distance from the bus waveguide 608 by electrostatic force, where the second distance is less than the first distance. For example, at the second distance, the coupling efficiency between the bus waveguide 608 and the optical antenna 616 via the coupling waveguide 614 can be greater than 50% (e.g., on).

[0099] In other words, Figure 6 This is a schematic diagram of a single MEMS switch 600 consisting of a movable optical coupler 614 and a fixed optical antenna 616. The optical coupler 614 can be moved close enough to the bus waveguide that a sufficient amount of light will be coupled outward from the bus waveguide 608 to the coupler waveguide 614. An example of such an optical coupler could be a tapered waveguide, and an electrostatically driven cantilever could move the optical coupler up and down. The optical antenna 616 is on the same layer as the optical coupler, but it is fixed. Light from the optical coupler can be emitted into free space via the optical antenna, and vice versa; light from free space can also be coupled back to the optical coupler via the optical antenna, and then further coupled back to the bus waveguide.

[0100] The MEMS switch includes a substrate 700 (such as a silicon substrate) having an insulating layer 702 (such as silicon dioxide). On top of the insulating layer 702 is a silicon layer 704. The first three layers (700, 702, 704) can be a silicon-on-insulator (SoI) substrate. The next layer can be an oxide 706, such as a low-temperature oxide (LTO), used to form anchor points. The top layer can be a silicon layer 708, such as a polycrystalline silicon layer deposited via plasma-enhanced chemical vapor deposition (PECVD) or low-pressure chemical vapor deposition (LPCVD). In this embodiment, structures such as a bus waveguide 608 and a MEMS actuation electrode 610 are in the silicon layer 704, while the MEMS spring 612, coupling cantilever 614, reactive electrode, and optical antenna 616 are in the polycrystalline silicon layer 708.

[0101] Figure 7A It is in an idle state. Figure 6 A cross-sectional view of the optically coupled cantilever of the MEMS switch (along lines 7A / 7B). When in an idle or off state, when the voltage difference between the reactive electrode and the actuating electrode is less than a lower threshold, the cantilever of the polysilicon layer 708 can be a first distance 710 from the bus waveguide of the silicon layer 704. Furthermore, the coupling efficiency between the bus waveguide 608 and the optical antenna 616 via the coupling waveguide 614 is less than 1% (e.g., off).

[0102] Figure 7B It is in an actuated state. Figure 6 A cross-sectional view of the optically coupled cantilever of the MEMS switch (along lines 7A / 7B). When in the ON state, when the voltage difference between the reactive electrode and the actuating electrode is greater than an upper threshold, the cantilever of the polysilicon layer 708 can be positioned at a second distance 712 from the bus waveguide of the silicon layer 704. Furthermore, the coupling efficiency between the bus waveguide 608 and the optical antenna 616 via the coupling waveguide 614 is greater than 50% (e.g., when ON).

[0103] Figure 7C It is in an idle state. Figure 6 A cross-sectional view of the fixed optical antenna of the MEMS switch (along line 7C / 7D). When in the off state, the optical antenna of the polysilicon layer 708 can be substantially separated from the bus waveguide of the silicon layer 704 by a first distance.

[0104] Figure 7D It is in an actuated state. Figure 6 A cross-sectional view of the fixed optical antenna of the MEMS switch (along line 7C / 7D). When in the ON state, the optical antenna of the polysilicon layer 708 is essentially maintained at a first distance from the bus waveguide of the silicon layer 704.

[0105] Figure 7A-D illustrates the cross-sections of the optical coupler and optical antenna in their on and off states, respectively. An advantage of this concept is that it imposes fewer design constraints on MEMS switch designs than current prior art. LiDAR systems require very high switching / movement speeds at their operating frequencies. This translates to constraints on translational quality, which necessitates trade-offs between antenna and coupler designs. However, in this disclosure, the antenna remains stationary and can therefore be designed with much greater freedom; for example, it can have a larger in-plane extension perpendicular to the bus waveguide, which translates to a more favorable narrower emitted beam distribution. For example, for Figure 6 In this design, the sector angle of the optical antenna can be larger, and the area of ​​the antenna along the bus waveguide and across the waveguide can be larger, resulting in a narrower output beam. A narrower beam helps to achieve better angular resolution in beam control.

[0106] If the antenna is not fixed, then preferably the antenna area will be limited to 30×30µm. 2 Or even smaller, there are no such limitations when the antenna is fixed. Furthermore, optical antennas can have greater freedom in terms of period and aspect ratio, which can improve their transmission efficiency. For example, since there are no hard and fast restrictions on the surface area and mass of a fixed antenna, it can have a larger extension along the waveguide, meaning a larger period. The aspect ratio is limited by the antenna mass. Without mass constraints, the aspect ratio can be designed primarily based on transmission efficiency rather than the trade-off between transmission efficiency and antenna mass. And the optical coupler can be designed with a smaller size and lighter weight without the antenna being movable; therefore, fast switching operations and optimized output beam quality can be achieved in such MEMS switch designs.

[0107] In another embodiment, more than one coupling cantilever can be coupled to each antenna. They can be connected to opposite ends of the antennas, thus providing separate transmit and receive channels. The transmit cantilever will be oriented towards the laser source, while the receive cantilever will be oriented towards the photodetector using the same waveguide used for optical coupling or using a separate waveguide. The separate transmit and receive channels can operate independently, enabling additional functionality. For example, light can be received from several pixels surrounding the current transmitting pixel, thus improving overall light collection efficiency.

[0108] MEMS switch arrays can be organized into rectangular patterns in optical terminals. Figure 8 ( ), circular patterns or other patterns. Combined with a lens, the terminal can be used as a light emitter, where the emitted beam is guided in different directions (e.g., Figure 8 ). Figure 8This is a perspective view of an optical switch array system 800 that transmits optical signals. Here, the substrate 802 can be a monolithic chip, such as a silicon chip, silicon-on-insulator (SoI) chip, silicon carbide chip, silicon nitride chip, or other monolithic MEMS chip, or the substrate can be a multi-chip module on a substrate. Each optical antenna 806 is configured to be aligned with bus waveguides 810a, 810b, 810c; for example, in this embodiment, there are a first bus waveguide 810a, a second bus waveguide 810b, and a third bus waveguide 810c. In this embodiment, each bus waveguide 810a, 810b, 810c is coupled to the main bus waveguide via a type I switch 818. It is coupled to a light source 814 (e.g., a laser, LED, etc.) such that light emitted from the light source 814 travels along direction 812 and is distributed to the optical antenna 806 via the type I switch 818. Located near the chip is a lens 804, which is configured to generate a collimated beam 816 from the optical antenna 806 via the lens 804. In this embodiment, the beam 816 can be collimated by translating the lens 804 along an axis 808 perpendicular to the substrate 802 and the optical antenna 806, or by translating the substrate 802 and the optical antenna 806 along an axis 809 perpendicular to the lens 804.

[0109] Such a terminal can also function as an optical receiver, capable of receiving beams returning from all directions and coupling the beams back to the PIC (Photonic Components). Figure 9 ). Figure 9 This is a perspective view of an optical switch array system 900 for receiving optical signals. Here, the substrate 902 can be a monolithic chip, such as a silicon chip, silicon-on-insulator (SoI) chip, silicon carbide chip, silicon nitride chip, or other monolithic MEMS chip, or the substrate can be a multi-chip module on a substrate. Each optical antenna 906 is configured to be aligned with bus waveguides 910a, 910b, 910c; for example, in this embodiment, there are a first bus waveguide 910a, a second bus waveguide 910b, and a third bus waveguide 910c. In this embodiment, each bus waveguide 910a, 910b, 910c is coupled to the main bus waveguide via a type I switch 918. It is coupled to a photodetector 924 (e.g., a photodiode, phototransistor, CCD, etc.) such that as light travels along direction 922, light is collected from the photodetector 924 and collected via the type I switch 918, which is focused by the optical antenna 906. Located near the chip is a lens 904, which is configured to focus the light beam 920 onto the optical antenna 906. In this embodiment, the light beam 920 can be focused by translating the lens 904 along an axis 908 perpendicular to the substrate 902 and the optical antenna 906, or by translating the substrate 902 and the optical antenna 906 along an axis 909 perpendicular to the lens 904.

[0110] Such a terminal can also function as a transceiver, capable of both transmitting and receiving beams. Figure 10 ). Figure 10 This is a perspective view of an optical switch array system 1000 for receiving and transmitting optical signals. Here, the substrate 1002 can be a monolithic chip, such as a silicon chip, silicon-on-insulator (SoI) chip, silicon carbide chip, silicon nitride chip, or other monolithic MEMS chip, or the substrate can be a multi-chip module on a substrate. Each optical antenna 1006 is configured to be aligned with bus waveguides 1010a, 1010b, and 1010c; for example, in this embodiment, there are a first bus waveguide 1010a, a second bus waveguide 1010b, and a third bus waveguide 1010c. In this embodiment, each bus waveguide 1010a, 1010b, and 1010c is coupled to the main bus waveguide via a type-I switch 1018. It is coupled to a photodetector 1024 (e.g., a photodiode, phototransistor, CCD, etc.) such that when light travels along direction 1022, light is collected from the photodetector 1024 and then collected via a type I switch 1018, which is focused by the optical antenna 1006. Near the chip is a lens 1004, which is configured to focus the light beam 1020 from the optical antenna 1006 via the lens 1004. In this embodiment, the light beam 1020 can be focused by translating the lens 1004 along an axis 1008 perpendicular to the substrate 1002 and the optical antenna 1006, or by translating the substrate 1002 and the optical antenna 1006 along an axis 1009 perpendicular to the lens 1004. Furthermore, it is coupled to a light source 1014 (e.g., a laser, LED, etc.) such that light emitted from the light source 1014 travels along direction 1012 and is distributed to the optical antenna 1006 via the type I switch 1018. Located near the chip is a lens 1004, which is configured to generate a collimated beam 1016 from the optical antenna 1006 via the lens 1004. In this embodiment, the beam 1016 can be collimated by translating the lens 1004 along an axis 1008 perpendicular to the substrate 1002 and the optical antenna 1006, or by translating the substrate 1002 and the optical antenna 1006 along an axis 1009 perpendicular to the lens 1004. If such a terminal operates only as a transmitter, a separate optical photodetector or photodetector array can be used, or, for example... Figure 9 The receiver shown is used as a receiver. Similarly, if such a terminal is used only as a receiver, then other similar... Figure 8 The light emitters, emitter arrays, or emitters shown can be used as stand-alone emitters.

[0111] While not limited to the presented embodiments, in the above design embodiments, the lens and / or MEMS switch array chip can be integrated with a mechanical structure such that one or both of them can move along the z-direction, as... Figure 8-10As shown. The advantage of this freedom is the ability to adjust the distance between the lens and the MEMS switch array chip to maximize the emission efficiency from each pixel and the reception efficiency to each pixel.

[0112] The proposed system can be used in chip-based lidar systems, including time-of-flight (ToF) and frequency-modulated continuous wave (FMCW) operations. In the chip-based lidar system, light is coupled to a waveguide of the PIC and then distributed into sub-waveguides. The proposed MEMS switch can be used with other types of binary switches (…). Figure 11 or split-path optical tree ( Figure 12 ) or switches and branch optical trees ( Figure 13 They are combined for use in light distribution. Figure 11 This is a perspective view of an optical switch array system 1100 including at least two types of optical switches. Here, a substrate 1102 with a cantilevered coupling switch is illustrated, which is coupled to an optical antenna 1106 configured to be aligned with bus waveguides 1110a, 1110b, and 1110c. For example, in this embodiment, there are a first bus waveguide 1110a, a second bus waveguide 1110b, and a third bus waveguide 1110c. In this embodiment, each bus waveguide 1110a, 1110b, and 1110c is coupled to the main bus waveguide via a type I switch 1118.

[0113] Figure 11 A layout with two types of binary switches is shown. Taking the transmitting terminal as an example, light propagates in the main waveguide. At the intersection of the main waveguide and the row waveguide, a Type I switch selectively guides the light into a selected row (in this example, the row of waveguide 1110b is selected). The light then propagates in the selected row waveguide until it reaches the MEMS switch (switch type II) in the on state and is emitted. The Type I switch can be a MEMS switch or other switches, such as a thermo-optic switch, an electro-optic switch, etc. Figure 12 The layout with a branch tree and binary MEMS switches is shown. Figure 12 This is a perspective view of an optical switch array system 1200 including a branching tree and optical switches. Here, a substrate 1202 with cantilevered coupling switches is illustrated, which are coupled to an optical antenna 1206 configured to align with bus waveguides 1210a, 1210b, and 1210c. For example, in this embodiment, there are a first bus waveguide 1210a, a second bus waveguide 1210b, a third bus waveguide 1210c, and a fourth bus waveguide 1210d. In this embodiment, each bus waveguide 1210a, 1210b, and 1210c is coupled to the main bus waveguide via a branching tree 1218. Furthermore, Figure 12The diagram illustrates a cantilever coupling and optical antenna 1206a in a closed state and a cantilever coupling and optical antenna 1206b in an open state, such that when the coupling cantilever and optical antenna 1206b are open, light 1216 is radiated from the optical antenna 1206b via the coupling cantilever coupled to the bus guide 1210c. The difference between these two arrangements is that in the branching tree arrangement, the optical power from the laser is uniformly distributed in the waveguide, while in the combined binary switch arrangement, the light from the laser is selectively guided to the desired waveguide.

[0114] These two layouts can be combined into a third layout, such as... Figure 13 As shown. Figure 13 This is a perspective view of an optical switch array system 1300 including a branch tree and at least two types of optical switches. Here, a substrate 1302 with a cantilevered coupling switch is illustrated, which is coupled to an optical antenna 1306 configured to be aligned with bus waveguides 1310a, 1310b, 1310c, 1310d, 1310e, 1310f, 1310g, 1310h, 1310i, 1310j, 1310k, and 1310l. For example, in this embodiment, a first bus waveguide 1310a, a second bus waveguide 1310b, and a third bus waveguide 1310c are present. In this embodiment, each bus waveguide 1310a, 1310b, 1306c, 1306d, 1306e, 1310f, 1310g, 1306h, 1306i, 1306j, 1310k, and 1306l is coupled to the main bus waveguide via a branch tree 1318 and a type-I switch 1328. Furthermore, Figure 13 The diagram illustrates a cantilever coupling and optical antenna 1306a in the off state, and cantilever coupling and optical antennas 1306b, 1306c, 1306d, and 1306e in the on state, such that when the coupling cantilever and optical antennas 1306b, 1306c, 1306d, and 1306e are open, light is radiated from optical antennas 1306b, 1306c, 1306d, and 1306e via coupling cantilevers coupled to bus guides 1310b, 1310e, 1310h, and 1310j. In this arrangement, light from the laser is distributed to several sections of the waveguide subarray, and then in each waveguide subarray, binary switches are used to selectively guide the light to the desired waveguide. This arrangement allows the MEMS switches in the various subarrays to be controlled independently and simultaneously. All of these arrangements can operate in a MEMS switch array-based transmit, receive, and transceiver terminal.

[0115] One of the advantages of MEMS switch arrays is their relatively simple control electronics. Figure 14 and Figure 15Two examples of electronic control of electrostatically driven MEMS switch arrays are shown.

[0116] Figure 14 This is a diagram of a switch array system 1400 configured to independently address rows and columns. The system 1400 addresses columns via column contact controller 1404 and rows via row contact controller 1406. In this diagram, column contact controller 1404c is enabled, thus turning on a selected or all switches associated with that column, and row contact controller 1406.3 is enabled, thus turning on the waveguide associated with that switch. The result includes turning on optical switch 1408, allowing light 1410 to be emitted from individual optical switches in the array. Figure 15 This is a diagram of a switch array system 1500 configured to simultaneously address subarrays. The system 1500 addresses columns via column contact controllers 1504 and rows via row contact controllers 1506. In this diagram, column contact controller 1504b is enabled, thus turning on selected or all switches associated with that column, and row contact controllers 1506.11, 1506.8, 1506.5, and 1506.3 are enabled, thus turning on the waveguides associated with these switches. The result includes the opening of optical switches 1512a, 1512b, 1512c, and 1512d, and enabling light 1514a, 1514b, 1514c, and 1514d to be emitted from individual optical switches in the array.

[0117] In other words, one way to drive MEMS switches in an array is, of course, to address each switch individually. Therefore, if there are M×N switches in the array, where M is the number of rows and N is the number of columns, then M×N controls will be needed. An example method to simplify control is to address rows and columns (e.g., ...). Figure 14 As shown in the diagram, this allows M×N switches to require only M+N controls. Figure 14 In this example, a switchable pixel that is emitting light is enabled by applying an appropriate voltage to row 1406 and column 1404. Another example method is to divide the MEMS switch array into subarrays and address the switches in multiple subarrays simultaneously, such as... Figure 15 As shown. In Figure 15 In this array, four switchable pixels emit light simultaneously, and they are enabled by applying appropriate voltages to columns 1504, rows 3, 5, 8, and 11 to drive the corresponding MEMS switches. Of course, the subarrays can also be addressed individually. All these electronic control methods can operate in a MEMS switch array-based transmit, receive, and transceiver terminal. Figure 14 and Figure 15 The control method shown has the advantage of simplicity. Compared to a separately controlled switch, the number of controls is significantly reduced.

[0118] Figure 16 This is a perspective view of the bus waveguide and corresponding coupler waveguide on the optical switch 1600. The substrate 1602 supports the bus waveguide 1604, and aligned with the bus waveguide 1604 is a cantilever coupler 1610, separated from the bus waveguide 1604 by a vertical gap 1606. The cantilever coupler 1610 may be tapered, giving it a narrow tip 1608 and a wider base 1612. For example, the tip 1608 may be a point, a rounded tip, or have a blunt end, wherein the ratio of the tip 1608 to the base 1612 includes 1:3, 1:4, 1.5, etc. For example, the tip width 1608 may be 0.08, 0.1, 0.15, or 0.2 μm, while the base 1612 may be 0.2, 0.3, 0.4, or 0.5 μm, etc. The length of the cantilever coupler 1610 allows it to be deflected to reduce the gap 106, resulting in a coupling efficiency between the waveguide 1604 and the cantilever coupler 1610 that is above a threshold, such as 50%, 60%, or greater. It should be noted that typically two actuation electrodes are on a substrate 1602 parallel to the bus waveguide 1604, with one electrode on either side of the bus waveguide 1604, and the length of the electrode is approximately equal to the length of the cantilever coupler 1610. Similarly, typically two reaction electrodes are on the cantilever coupler 1610, substantially parallel to the bus waveguide 1604, with one electrode on either side of the cantilever coupler waveguide, which is outlined by a narrow tip 1608 and a wide base 1612. The length of the reaction electrode is approximately equal to the length of the cantilever coupler 1610.

[0119] Figure 17 This is a graphical representation of the coupled field distribution with respect to distance 1700. It illustrates the field distribution when the coupled cantilever is open and energy is transferred from the bus waveguide to the cantilever waveguide. This illustration is related to a length of 7.5 μm. Figure 16 The cantilever coupler is associated with this, illustrating the transfer of energy along the length of the cantilever coupler. Similarly, Figure 18 This is a series of two-dimensional graphical representations of the coupled field distribution with respect to the propagation distance. This illustrates the field distribution when the coupled cantilever is open and energy is transferred from the bus waveguide. The illustration is related to a length of 7.5 μm. Figure 16 The cantilever coupler is associated with this, illustrating the transfer of energy along the length of the cantilever coupler.

[0120] Figure 19 This is a graphical representation of the coupling efficiency 1902 with respect to the coupling tapered length 1904 1900. This illustrates the coupling efficiency 1906 when coupling cantilevers with various tapered lengths are opened and energy is transferred from the bus waveguide. This diagram is consistent with... Figure 16 The association of cantilever couplers with various tapered lengths illustrates the transfer of energy along the length of the cantilever coupler. Figure 20This is a graphical representation of the transmission loss 2002 with respect to a wavelength 2004. It illustrates the transmission loss 2002 when the coupled cantilever is open and energy is transferred from the waveguide. The diagram is illustrated with a length of 7.5 μm. Figure 16 The cantilever coupler is associated with the transmission loss 2002 over the length of the cantilever coupler. As stated in this disclosure, the cantilever coupler is not limited to silicon; however, in this example, the cantilever coupler is a silicon cantilever coupler.

[0121] Figure 21 This is a graphical representation 2100 of the energy loss 2102 with respect to the gap size 2104. In this diagram, the energy to the bus 2106 has a minimum value at approximately 180 nm, at which point the energy to the MEMS 2108 begins to deflect and decrease. Based on this, during the "on" state, the gap is maintained essentially at 180 nm to ensure maximum coupling efficiency with the MEMS waveguide. In the "off" state, the gap returns to a distance above a certain level (e.g., 650 nm), such that the energy received to the MEMS is less than -30 dB. Figure 22 It is radiation diagram 2206 about angle β2202 (e.g.) Figure 5B The angles shown in the diagram are 562 and θ2204 (e.g.) Figure 5B The graphic representation of an angle of 560° is 220°. Figure 22 In the diagram, energy intensity is normalized to 1 based on grayscale, and contour lines are shown as radiation map 2206.

[0122] Figure 23 This is a side view of an optical system 2300 including a waveguide grating 2302 in a waveguide 2304. The waveguide can be a material such as silicon, polycrystalline silicon, silicon nitride, silicon carbide, silicon dioxide, or other materials (e.g., waveguides) that can be configured to conduct energy. The grating 2302 includes a gap 2310 that can vary from 100 nm to 500 nm or greater at a pitch 2312, which can be a factor of 1.5, 2.0, or 2.5 times the distance of the gap 2310. The gap distance can vary in a plane perpendicular to the underlying waveguide. The waveguide performance can be evaluated along a plane 2314 that is substantially parallel to the substrate and at a distance 2316 above the substrate. Energy is diffracted substantially into free space at an angle θ2318 incident on the plane 2314. Figure 24 This is a perspective view of a cantilever spring 2400, illustrating the displacement caused by the bias between the reactive and actuating electrodes at a given voltage. For example, a 40V voltage difference between the reactive and actuating electrodes indicates a displacement of approximately 620nm. Figure 25 This is a graphical representation of the displacement along the Z-axis 2502 with respect to the switching speed 2504 2500. This graphical representation shows the displacement along the Z-axis at different locations on the cantilever waveguide.Figure 24 The displacement along the Z-axis. In this example, three distributions are shown: the displacement near the tip 2506 of the cantilever waveguide, the displacement in the middle towards the end 2508 of the cantilever waveguide, and the displacement near the end connected to the optical antenna 2510.

[0123] Figure 26 This is a top view of a switch array layout 2600 with multiple optical switches on a substrate 2602 and a detailed illustration of a single element 2604. The optical switches include a waveguide 2606 coupled to the substrate 2602, and also coupled to the substrate are anchor points 2608. A MEMS spring 2610 is shown coupled to one anchor point 2608, while an optical grating 2612 is coupled to another anchor point 2608. The MEMS spring 2610 has a first end coupled to the anchor point 2608 and a second end coupled to a cantilever coupler 2614 suspended above the bus waveguide 2606. An actuation electrode is mounted to the substrate 2602 on either side of the bus waveguide 2606, and a reaction electrode configured to cooperate with the actuation electrode is mounted on either side of the cantilever coupler 2614. In this illustration, the optical grating / optical antenna 2612 and the cantilever coupler 2614 are on the same layer. In an optical switch array system for beam control applications, one embodiment includes a system in which each optical switch consists of a movable MEMS optical coupler on a suspension layer and an optical antenna on a substrate layer. In various applications, including lidar, switch arrays supporting MEMS optical couplers can be used to couple light from a waveguide on a photonic integrated circuit (PIC) chip into free space (or vice versa).

[0124] Figure 27A This is a perspective view of a switch array 2700 having a movable optical coupler 2714 on a suspension layer 2716 and a fixed optical antenna 2712 on a substrate layer 2702. Figure 27B This is a top view of a switch array 2700 having a movable optical coupler on a suspension layer and a fixed optical antenna on a substrate layer. The optical switch includes a waveguide 2706 coupled to a substrate 2702, and also coupled to the substrate is an anchor point 2708. A MEMS spring 2710 is shown coupled to one anchor point 2708. The MEMS spring 2710 has a first end coupled to the anchor point 2708 and a second end coupled to a cantilever coupler 2714 via a suspension layer 2716 suspended above the bus waveguide 2706. An actuation electrode 2718 is mounted to the substrate 2702 on either side of the bus waveguide 2706, and a reaction electrode is mounted on either side of the cantilever coupler 2714, configured to cooperate with the actuation electrode 2718. In this illustration, an optical grating / optical antenna 2712 is on the same layer as the bus waveguide 2706.

[0125] The MEMS switch array can be enabled by a movable MEMS optocoupler 2714 on the suspension layer 2716 and a fixed optical antenna 2712 on the substrate layer 2702. Figure 27A and Figure 27B Perspective and top views of this MEMS switch are provided. Each MEMS switch consists of a movable MEMS optocoupler 2714 on a suspension layer 2716 (which we call the "MEMS layer") and an optical antenna 2712 on a substrate layer 2702. Here, the concept is illustrated using the grating antenna 2712 as an example; other optical antenna designs are also applicable to this concept. When in the off state, the MEMS layer, reactive electrodes, and cantilever coupler 2714 are away from the bus waveguide 2706 and actuation electrode 2718, allowing light to propagate undisturbed within the bus waveguide 2706. When in the on state, the reactive electrodes are actuated, and the MEMS optocoupler 2714 is moved closer to the bus waveguide 2706, causing light to couple to the coupler waveguide 2714 on the MEMS layer. The reactive electrodes and the second cantilever coupler descend into the separated bus waveguide, which connects to the optical antenna 2712, which transmits the signal into free space. When a signal is received, this optical path is reversed.

[0126] Figure 28A This is a cross-sectional view of the movable optical coupler in Figure 27 (along line 28A / B) when it is in the off position. When off, the MEMS layer (including the reactive electrode) 2716 is positioned a first distance above the top of the bus waveguide 2706. This distance is due to the voltage difference between the actuation electrode 2718 and the reactive electrode being below a voltage threshold, causing the cantilever coupler 2714 to be positioned away from the bus waveguide 2706. This first distance allows light to propagate substantially undisturbed within the bus waveguide 2706.

[0127] Figure 28B This is a cross-sectional view of the movable optical coupler in the ON position (along line 28A / B) of Figure 27. When ON, the MEMS layer (including the reactive electrodes) is positioned at a second distance above the top of the bus waveguide 2706. This second distance is caused by the voltage difference between the actuation electrode 2718 and the reactive electrode exceeding a voltage threshold, causing the cantilever coupler 2714 to be pulled towards the bus waveguide 2706. At this second distance, light is coupled through the reactive electrodes and the second cantilever coupler to the coupler waveguide 2714 on the MEMS layer. The second cantilever coupler descends to the separated bus waveguide, which connects to the optical antenna 2712, which transmits the signal into free space. When a signal is received, this optical path is reversed.

[0128] Figure 28A and Figure 28BThe diagram illustrates a cross-section of the actuated optical coupler. The advantage of this concept is that the optical antenna is located on the substrate layer, which does not increase the weight of the suspension structure compared to other structures and presents fewer manufacturing challenges. LiDAR systems require very high switching / movement speeds at their operating frequencies. This translates to limitations on translational quality. However, in this disclosure, the optical antenna remains on the substrate layer, so its size does not affect the operating speed. Therefore, the antenna can have a larger footprint to form a favorable Gaussian beam profile, and emission efficiency can be optimized through flexible grating periods and / or duty cycles. The coupler waveguide on the suspension layer is small and lightweight, which further ensures fast switching speeds. The optical coupler can be electrostatically grounded, piezoelectrically grounded, or driven by other mechanisms. It can be a double cantilever with the middle section anchored so that both ends can be operated together, or both ends can be operated independently. Moreover, it can be a beam (e.g., where the entire coupler waveguide moves during operation) that is part of the beam. Figure 27B (As shown).

[0129] The concepts described herein can be implemented in alternative embodiments. Another embodiment is shown below. Figure 29 and Figure 30 . Figure 29 This is a top view of a switch array layout 2900 having a movable optical coupler 2914 on a suspension layer and a fixed optical antenna 2912 on a substrate layer 2902, with individual elements shown in detail. The optical switch includes a waveguide 2906 coupled to the substrate 2902, and also coupled to the substrate is an anchor point 2908. A MEMS spring 2910 is shown coupled to one anchor point 2908. The MEMS spring 2910 has a first end coupled to the anchor point 2908 and a second end coupled to the cantilever coupler 2914, both couplings being via a suspension layer 2916 suspended above the bus waveguide 2906. An actuation electrode 2918 is mounted to the substrate 2902 on either side of the bus waveguide 2906, and a reaction electrode configured to cooperate with the actuation electrode 2918 is mounted on either side of the cantilever coupler 2914. In this illustration, the optical grating / optical antenna 2912 is on the same layer as the bus waveguide 2906.

[0130] Figure 30This is a top view of a switch array layout 3000 having a movable optical coupler on a suspension layer and a fixed optical antenna on a substrate layer, with individual elements detailed. The optical switch includes a waveguide 3006 coupled to a substrate 3002, and also coupled to the substrate is an anchor point 3008. A MEMS spring 3010 is shown coupled to one anchor point 3008. The MEMS spring 3010 has a first end coupled to the anchor point 3008 and a second end coupled to a cantilever coupler 3014, both couplings being via a suspension layer 3016 suspended above the bus waveguide 3006. An actuation electrode 3018 is mounted to the substrate 3002 on either side of the bus waveguide 3006, and a reaction electrode configured to cooperate with the actuation electrode 3018 is mounted on either side of the cantilever coupler 3014. In this illustration, an optical grating / optical antenna 3012 is on the same layer as the bus waveguide 3006.

[0131] Figure 29 The layout consists of a linear waveguide array and an optical antenna array 2912 located at a certain offset distance from waveguide 2906. In this design, coupler waveguide 2914 is oriented to pick up light from bus waveguide 2906 and place it into antenna 2912. Alternatively, Figure 30 The layout consists of a curved bus waveguide array 3006 and an optical antenna array 3012 aligned with the straight portion of the bus waveguide 3006. In this design, the coupler waveguide is straight.

[0132] Figure 31This is a top view of an element in a switch array layout 3100 having an optical coupler 3126 on a suspension layer 3124 and a fixed optical antenna 3104 on a substrate layer. The optical antenna 3104 covers an angle 3106, such as 45 degrees, 60 degrees, or 90 degrees, and has a base or tapered section 3108 after which a grating begins. The optical coupler 3126 can be a single element or can consist of multiple segments. Here, the optical coupler 3126 has three segments: the first segment 3112 is pulled down to couple with the optical antenna 3104 when activated; the second segment 3114 connects the first segment 3112 to the third segment 3116; and the third segment 3116 is moved downwards to couple with the bus waveguide 3102. The second segment 3114 can be fixed and directly coupled to the anchor point, such that the distance from the second segment 3114 to the substrate does not move. Alternatively, in another embodiment, the second segment 3114 is floating and moves with the movement of the first segment 3112 and the third segment 3116. The bus waveguide 3102 can have a width 3118 at the point where the tip of the optocoupler 3126 will couple when activated, and this width can narrow to a width 3120 before a turn of radius 3122, such that the turn is configured to be substantially thermally adiabatic. Transmission through the optocoupler 3126 can have a first loss 3128 through the third segment 3116, a second loss 3130 through the second segment 3114, and a third loss 3132 through the first segment 3112. These losses can be a small fraction of dB; for example, the losses in the first segment 3128 and the third segment 3132 can be 0.1 dB, while the losses in the second segment 3130 can be less than 0.02 dB. Figure 32 yes Figure 31 A cross-sectional view of element 3200. Here, optical coupler 3126 is coupled to suspension layer 3124 and aligned above bus waveguide 3102. Optical bus waveguide 3102 has a height 3210, and suspension layer 3124 is located at a distance 3212 above bus waveguide 3102, which varies with state; for example, distance 3212 can be less than 0.2 micrometers when on and greater than 0.6 micrometers when off. Suspension layer 3124 may have a thickness 3214 so that it can provide support but still allow optical coupling between bus waveguide 3102 and optical coupler 3126. Optical coupler 3126 may have a thickness 3216.

[0133] Figure 31 and Figure 32 It shows Figure 30 An example of a single MEMS optical coupler and a fixed grating antenna in the layout. Figure 31 The dimensions marked in the text are examples. Figure 17 and Figure 18The coupling performance of this device with a MEMS optical coupler 180 nm from the bus waveguide is shown, and Figure 33 The electric field distribution on the grating is shown. Figure 33 This is a graphical representation of the field distribution 3300 of the grating antenna with respect to the X coordinate 3304 and the Y coordinate 3302. Figure 34 It is an optical coupler 3400 (such as...) Figure 31 A perspective view illustrating the displacement of an optical coupler. Figure 34 This is a simulation of the displacement of a MEMS optocoupler. Generally, the optical coupling length ranges from a few micrometers to several hundred micrometers depending on the design, and the distance between the coupler waveguide and the bus waveguide / antenna waveguide ranges from a few nanometers to a few micrometers in the on state.

[0134] Some optical antennas have a non-zero emission angle θ, such as Figure 35 and Figure 36 As shown, this may cause problems with the amplitude array terminal. Figure 35 This is a perspective view of the grating antenna 3500 of the MEMS structure 3502, illustrating the emission angles β3504 and θ3506. Figure 36 This is a graphical representation of intensity 360° with respect to emission angles β360°2 and θ360°4. The figure shows 10 cycles, with the intensity represented in grayscale.

[0135] One solution to this problem is to sacrifice the optical antenna's radiation efficiency and far-field beam quality to achieve a zero emission angle. A second solution is to add additional structures to force the light to emit perpendicularly, including but not limited to bottom reflectors, additional top dielectric layers, and ultra-fine etched grooves. A third solution is to design lenses accordingly to compensate for non-zero emission angles. However, due to manufacturing variations, this approach is not flexible enough to address different emission angles. Here, we propose using mirrors or prisms between the antenna array and the lens to compensate for non-zero emission angles, such as... Figure 37 , Figure 38 , Figure 39 As shown. Figure 37 The illustration shows a side view 3900 of a reflector used to compensate for a non-zero antenna emission angle. Here, a telecentric lens 3902 is used to collimate light from an antenna array or photonic integrated circuit through the reflector into free space (emission), or to reflect light from the reflector 3904 onto the antenna array or photonic integrated circuit (PIC) 3910 (reception). Here, a virtual image 3906 of the PIC 3910 is shown on a virtual plane 3908. Figure 38This is a side view of an optical prism system 4000 used to compensate for non-zero antenna emission angles. Here, a telecentric lens 4002 is used to collimate light from the antenna array into free space (emission) through the prism, or to focus light onto the antenna array 4004 (antennas A1, A2, A3, A4, A5) (PIC) (receiver) through the prism. Figure 39 The diagram illustrates a side view 4100 of a microprism array used to compensate for non-zero antenna emission angles. Here, a telecentric lens 4102 is used to collimate light from the antenna array into free space (emission) through the microprisms, or to focus light onto the antenna array 4104 (A1, A2) (PIC) (reception) through the microprisms.

[0136] Mirrors or prisms can bend light so that reflected or refracted rays enter the lens system at a zero angle of incidence. Because the mirrors or prisms can rotate, they can be adjusted during the calibration phase to compensate for manufacturing errors. Simultaneously, telecentric lenses can be used to match the tilted emission array. The advantage of this method is that it eliminates the need for complex lens designs.

[0137] The proposed system can be used in chip-based lidar systems, including time-of-flight (ToF) and frequency-modulated continuous wave (FMCW) operations. In the chip-based lidar system, light is coupled to a waveguide of the PIC and then distributed into sub-waveguides. Figure 40A This is a top view of an antenna array 4200 with a branch tree 4202 and an optical switch 4204. Figure 40B This is a top view of an antenna array 4230 with various switch types. In this example, there are type I switches 4206 and optical switches 4204. Figure 40C This is a top view of the antenna array 4360, which features a branching tree 4202 and various switch types, such as a type I switch 4206 and an optical switch 4204. The proposed MEMS switch can be used with the branching tree ( Figure 40A ) or other types of binary switches ( Figure 40B or switches and branch trees ( Figure 40C Combined for use in light distribution. Figure 40B The diagram illustrates a layout with two types of binary switches. Taking the transmitting terminal as an example, light propagates in the main waveguide. At the intersection of the main waveguide and the row waveguide, a Type I switch selectively guides the light into a selected row (the second row from the top is selected in the diagram). The light then propagates in the selected row waveguide until it reaches the on-state MEMS switch (switch type II) and is emitted. The Type I switch can be a MEMS switch or other switches, such as a thermo-optical switch, an electro-optical switch, etc. Figure 40AA layout with a branching tree is shown. The difference between the two layouts is that in the branching tree layout, the optical power from the laser is uniformly distributed throughout the waveguides, while in the combined binary switch layout, the light from the laser is selectively guided to a single waveguide at a time. These two layouts can be combined into a third layout, such as... Figure 40C As shown. In this layout, light from the laser is distributed to several sections of the waveguide subarray, and then in each waveguide subarray, a binary switch is used to selectively guide the light to the desired waveguide. This layout allows the MEMS switches in the various subarrays to be controlled independently and simultaneously. All of these layouts can operate in a MEMS switch array-based transmitter / receiver terminal. Figure 40B and Figure 40C In this layout, active rows are selected by type I switches, while active columns are selected by type II switches. Therefore, the control complexity of an M×N array is linearly related to the array size (O(M+N)), rather than quadratically (O(M×N)).

[0138] This section discloses MEMS switches and arrays for in-plane motion in optical coupling. In various applications, the proposed MEMS switches can be used to couple light from waveguides on a photonic integrated circuit (PIC) chip into free space.

[0139] Figure 41A This is a perspective view of a switch array with movable gratings that travel longitudinally with multiple stop positions. In this embodiment, gratings 4308a, 4308b, and 4308c travel longitudinally, resulting in multiple stop positions. The illustration shows three stop positions, 4308a, 4308b, and 4308c. In this embodiment, the neutral position can be 4308a, such that the grating will be moved to other positions 4308b and 4308c based on the voltage applied to the interdigital electrodes. Furthermore, the gratings can be configured such that the neutral position is in the middle, 4308b, such that a positive voltage across the interdigital electrodes moves the grating to one position (e.g., 4308a), and a negative voltage across the interdigital electrodes moves the grating to another position (e.g., 4308c). In this illustration, light travels downwards along waveguide 4304 and into three bus waveguides 4306a, 4306b, and 4306c. As previously mentioned, light can travel downwards via beam splitters or optical switches, and light can also travel in the opposite direction to 4304. Figure 41B This is a detailed perspective view of a movable grating 4314, which travels longitudinally 4312 to a position with multiple stop orientations from... Figure 41A The bus waveguide 4316 is supported by a substrate. The substrate supports an anchor 4318, which is coupled to the interdigital electrode 4320.

[0140] Figure 41C This is a perspective view of a switch array with a movable grating 4328 that travels longitudinally 4322 to bus waveguides 4326a, 4326b, and 4326c. The illustration shows two stopping positions, 4328a and 4328b. In this embodiment, the neutral position can be 4328a, such that the grating will be moved to another position 4328b based on the voltage applied to the interdigital electrodes. In this illustration, light travels downwards along waveguide 4324 and to the three bus waveguides 4326a, 4326b, and 4326c. As previously described, light can travel downwards via a beamsplitter or optical switch, and light can also travel in the opposite direction to 4324. Figure 41D It is a vertical journey from Figure 41C Detailed perspective view of the two movable gratings 4342 of the bus waveguide 4316. The bus waveguide 4316 is supported by a substrate. The substrate supports an anchor 4338, which is coupled to the interdigital electrode 4334. Figure 41E This is a top view of a movable grating 4342 that travels longitudinally 4332 along the interdigital electrode 4334 to the bus waveguide 4336. The bus waveguide 4336 is supported by a substrate. The substrate supports an anchor 4338, which is coupled to the interdigital electrode 4334. A spring 4340 is coupled to the grating 4342 on one side and to the anchor 4338 on the other side.

[0141] Figure 42A This is a perspective view of a switch array with a movable grating 4408 that travels laterally 4402 to bus waveguides 4406a, 4406b, and 4406c with multiple stop positions. In this embodiment, the grating 4408 travels laterally, resulting in multiple stop positions; the illustration shows three stop positions, 4408a, 4408b, and 4408c. In this embodiment, the neutral position can be 4408a, such that the grating will be moved to other positions 4408b and 4408c based on the voltage applied to the interdigital electrodes. Furthermore, the grating can be configured such that the neutral position is in the middle 4408b, such that a positive voltage across the interdigital electrodes moves the grating to one position (e.g., 4408a), and a negative voltage across the interdigital electrodes moves the grating to another position (e.g., 4408c). In this illustration, light travels downwards along waveguide 4404 and into three bus waveguides 4406a, 4406b, and 4406c. As previously mentioned, light can travel downwards via beam splitters or optical switches, and light can also travel in the opposite direction to 4404. Figure 42B This is a detailed perspective view of the movable grating 4408, which has a perspective view of the grating from... Figure 42AIn the case of multiple stop positions of the switch array, the transverse waveguide 4402 travels to bus waveguides 4406a, 4406b, and 4406c. Bus waveguides 4406a, 4406b, and 4406c are supported by a substrate. The substrate supports an anchor 4418, which is coupled to interdigital electrodes 4420. Figure 42C This is a top view of a movable grating 4442 that travels laterally via interdigitated electrodes 4434 to bus waveguides 4436a, 4436b, and 4436c. In this illustration, a spring 4440 is coupled to an anchor 4438, which is coupled to a substrate. The other end of the spring 4440 is coupled to the grating 4442 such that the force applied by the interdigitated electrodes 4434 moves the grating 4442 above the bus waveguides 4436a, 4436b, and 4436c as described above.

[0142] Figure 43 This is a perspective view of a switch array with movable gratings that travel laterally at 4502 with in-plane and out-of-plane stopping orientations relative to waveguides 4506a, 4506b, and 4506c. In this embodiment, light travels down along the bus waveguides in direction 4504 and is distributed to the three bus waveguides 4506a, 4506b, and 4506c. In this embodiment, the out-of-plane grating is shown as 4510 and is not aligned with any of the bus waveguides 4506a, 4506b, or 4506c. The in-plane grating is shown as 4508 and is aligned with the bus waveguides 4506a, 4506b, and 4506c, such that there is optical coupling between grating 4508 and bus waveguide 4506b.

[0143] Figures 41, 42 and Figure 43 Three examples of in-plane movable MEMS switches in amplitude array lidar applications are shown. In all three figures, grating antennas are used as examples to illustrate the switch concept, and other antenna designs are also applicable to these switch concepts. In all three designs, the MEMS switch layer is suspended above a bus waveguide layer. The gap between the MEMS switch layer and the bus waveguide layer is a few nanometers to several hundred nanometers, making the coupling efficiency between the MEMS switch and the bus waveguide sufficient to allow more than 50% of the light to be coupled from the bus waveguide to the MEMS switch layer. In Figure 41, the MEMS switch can move along the waveguide, and the pixel is a virtual pixel defined by the stopping orientation of the MEMS switch. Whenever the MEMS switch stops, light is coupled out from that orientation, and the virtual pixel is turned on. Depending on the size of the waveguide and the range of movement of the MEMS switch, there can be a ( Figure 41A and Figure 41B ) or more than one ( Figure 41C and Figure 41DThe MEMS switch covers a waveguide length. In Figure 42, the MEMS switch can move in a plane along the x-direction across multiple waveguides. Similar to the design in Figure 41, the pixels are also virtual pixels defined by the stopping orientation of the MEMS switch. Depending on the size of the waveguide array and the range of movement of the MEMS switch, a single MEMS switch can cover all or part of the waveguides in the array. One advantage of the MEMS switches shown in Figures 41 and 42 is that the switch moves in a plane, which is easier to implement than out-of-plane movable switches. Moreover, the virtual switch stops allow the switch to stop flexibly at any orientation along the movement path.

[0144] Figure 43 Another in-plane MEMS switch design is shown. Unlike the design in Figure 42, here the pixels are actual pixels defined by the relative overlap of the MEMS switches and the bus waveguide. In the off state, the switches are located outside the waveguide, and in the on state, the switches move to overlap with the waveguide. Its advantage is that the movement distance of each switch is small, making the switches easier to implement.

[0145] The proposed in-plane MEMS switches can also be organized into arrays and combined with lenses for beam control in optical transmitters, receivers, or transceiver terminals. All switch combination and branch tree combination concepts, as well as row / column wiring concepts, are also applicable to the proposed in-plane MEMS switches.

[0146] The concept of a vertically movable MEMS switch with a cantilever coupler and a fixed optical antenna presented in this disclosure requires stopping the cantilever coupler. For vertically movable MEMS switches (e.g., Figure 4A-4C , Figure 6 In applications requiring MEMS switch or optical cantilever to stop at a certain distance above the bus waveguide, control is needed. Mechanical stoppers (bumps) can be used to mechanically stop the MEMS switch. However, since the suspension layer contacts the mechanical stopper with each operation, the mechanical stopper may wear down, potentially reducing the system's optical coupling performance. Here, an electrostatically levitated system and method are used as the MEMS switch stopper in the MEMS switch optical coupling application.

[0147] Figure 44This is a perspective view of a switch 4600 that uses electrostatic levitation to control the coupling distance between a bus waveguide and a grating. The electrostatically levitated switch 4600 has a substrate 4602 that supports a bottom or repulsive electrode 4604, a bus waveguide 4606, a bottom center or active electrode 4608, and an anchor 4614. Supported on the bus waveguide 4606 is an optical grating 4610 suspended by a spring 4612 coupled to the anchor 4614. Located on the grating 4610 is a top or reactive electrode 4616. A method for controlling the stop orientation of a vertically movable MEMS switch using a non-mechanical limiter is described. Figure 44 The diagram illustrates a method utilizing electrostatic levitation (using a switchable MEMS grating as an example to explain the concept). In this design, a bottom center electrode and a top electrode are used to electrostatically drive the MEMS structure into or out of the pulled-in state. The bottom center electrode and top electrode are then held at the same voltage level (e.g., both grounded), and a larger positive voltage is applied to the bottom electrode. Therefore, the larger electric field generated by the bottom electrode voltage pushes the MEMS structure upwards and ultimately holds it at a certain distance above the bus waveguide. The advantage of this electrostatic levitation limiter is that the suspension layer does not physically contact the bottom bus waveguide layer, eliminating concerns about static friction or physical wear during MEMS operation. However, this method requires a relatively high voltage to hold the suspension layer in a specific orientation.

[0148] Another approach is to use a comb drive, an example of which is... Figure 45A and Figure 45B As shown in the image. Figure 45A This is a perspective view of a switch 4700 with a comb-like driver used to control the coupling distance between a bus waveguide 4706 and a grating 4710. The electrostatic comb-like levitating switch 4700 has a substrate 4702 that supports a bottom or active comb electrode 4704, a bus waveguide 4706, and an anchor 4714. Supported above the bus waveguide 4706 is an optical grating 4710 suspended by a spring 4712 coupled to the anchor 4714. Coupled to the optical grating 4710 is a top or reactive comb electrode 4708. Figure 45B It is along Figure 45A A cross-sectional view of the cut (47B) illustrating a comb driver, wherein the bottom or active comb electrode 4704 interdigitates with the top or reactive comb electrode 4708 of the adjacent bus waveguide 4706. In this illustration, the fins of the comb driver are perpendicular to the bus waveguide 4706, but the fins may also be configured to be parallel to the bus waveguide 4706.

[0149] Finger electrodes are formed on a movable suspension layer (top electrode) and a fixed substrate layer (bottom electrode). The direction of the electric field between the top and bottom electrodes can be controlled by the polarity of the voltage applied to the electrodes. When the voltage applied to the top electrode is higher than that to the bottom electrode, the electric field is downward, pulling the suspension layer towards the bus waveguide. Once it reaches a certain position, changing the voltage of the top electrode to be lower than that of the bottom electrode causes the electric field to rise, helping to overcome gravity and hold the suspension layer in that position. The advantage of the comb actuator is that it does not require the large voltage required for electrostatic levitation, and it is also a non-mechanical limiter.

[0150] This disclosure presents various designs of MEMS switches and switch arrays. These designs are used in optical transmitting, receiving, and transceiver terminals. Methods for integrating MEMS switches and switch arrays into chip-based LiDAR systems, as well as methods for packaging such systems, will now be described.

[0151] The chip-to-lidar system based on MEMS switch arrays integrates MEMS structures onto a silicon photonics platform. This combination of MEMS structures and silicon photonics platforms presents new challenges that are not present in MEMS-only or silicon-only systems. Therefore, system integration and packaging require careful design and handling. Figure 46 This is a cross-sectional view of a switch array system, illustrating the integration and packaging of a chip-based LiDAR module 4800 based on a MEMS switch array.

[0152] MEMS structures can have various failure mechanisms (e.g., dust, moisture), therefore, all components of the chip-to-LiDAR module need to be packaged together and hermetically sealed. The hermetically sealed LiDAR module 4800 includes: a heat sink / substrate platform 4802, a light source 4804 (e.g., laser, LED, or other common light sources), an optical coupling component 4806, a photonic integrated circuit (PIC) chip 4808 with MEMS switches and ASIC controls, a lens 4810, an anti-reflective inner coating 4812, an anti-reflective outer coating 4814, one or more photodetectors 4816 (e.g., photodiodes, phototransistors, charge-coupled devices, or other common photodetectors), and other necessary coupling components. The light source 4804 can be coherent and polarized.

[0153] Figure 46An example of system integration and packaging is shown. All components are integrated on a substrate platform with a heat dissipation mechanism and hermetically sealed in a package. The package cover includes a window area that is transparent to the wavelengths used in the LiDAR chip, so light can be emitted from the package and return to the PIC chip. This window area may cover part or all of the cover surface. Anti-reflective coatings on the inner and outer surfaces of the window help reduce reflections as light passes through the window. Different parts of the system can be packaged at different pressure levels and encapsulated with different gas compositions. For example, the MEMS switch array / PIC 4808 requires a certain pressure level (e.g., above 1 Torr) to induce damping so that the MEMS switch can stop in the orientation for switching on. To achieve this, a heavy gas (such as nitrogen, argon, etc.) is used to fill the chamber until the desired pressure level is reached. Outside this area (i.e., within the hermetically sealed module 4800), the pressure can be a vacuum pressure level (e.g., below 1 mTorr) to minimize the effects of particles and moisture. The hermetic sealing temperature of the 4800 should be below the temperature threshold level that may affect the performance of other components in the system (e.g., PIC 4808, light source 4804, photodetector 4816). For example, it is recommended that the sealing temperature be kept below 300°C so that the laser performance is not affected. Regarding ASIC integration, chip bonding via silicon throughput can minimize the impact of electrical paths on switching speed and switching performance.

[0154] This section presents several designs and concepts for MEMS switches and their arrays for optical coupling. These proposed structures can be used in optical terminals for beam control. Different designs and layout methods for MEMS switches and MEMS switch arrays are described here. All of these methods can be used to construct beam control terminals.

[0155] Figure 47 An example of a MEMS switch array design is shown in the figure. Figure 47 This is a perspective view of a dual-grating switch 4900 traveling laterally 4906 with its stop orientation in the plane of waveguides 4912a, 4912b, 4912c, and 4912d. The substrate 4902 has multiple type-I switches (e.g., 4910a, 4910b) for guiding light to bus waveguides 4912a, 4912b, 4912c, and 4912d. In this illustration, dual gratings 4914a and 4914b are aligned such that grating 4914a is aligned with bus waveguide 4912a, or grating 4914b is aligned with bus waveguide 4912b, such that light 4904 is coupled.

[0156] Here, a grating is used as an optical coupler / antenna integrated with a MEMS switch to illustrate this concept. Other optical coupler / antenna designs are also applicable to this concept. Figure 47 In the MEMS switch array shown, each MEMS switch carries two optical antennas and controls two pixels on top of two adjacent bus waveguides. Each MEMS switch can be driven horizontally and moves two grating couplers / antennas across the two waveguides in the x-direction. The MEMS switches have two orientations (4914a and 4914b): one grating overlaps with either of the two waveguides (one pixel is on, orientations 4914a and 4914b). For example, turning on the second pixel above waveguide 4912b turns on row switch 4910b and drives the MEMS switch to move the two grating couplers / antennas in the x-direction, such that one grating coupler / antenna has sufficient overlap with waveguide 4912b, and enough light can be coupled from waveguide 4912b to the grating and then emitted into free space. Depending on which pixel is to be turned on, the switch will be deflected until it reaches a stop against a mechanical spring (e.g., Figure 47 (A schematic diagram of a single switch is shown). A comb-driven actuator can be used to drive the in-plane motion of the switch. Since the grating is larger than the waveguide, the bouncing back and forth will have a very small impact on performance. Deflection can be achieved electrostatically, inductively, piezoelectrically, or similarly. The distance between the grating layer and the bus waveguide layer should be small enough to ensure that sufficient light can couple from the bus waveguide to the grating when the switch is in orientation 4914a or 4914b. The advantage of this design is that the number of MEMS switches is only half the number of pixels.

[0157] Figure 48 Another design for a MEMS switch array is shown, in which the MEMS switches are also driven to move horizontally along the x-axis, and one MEMS switch carries more than one optical coupler / antenna (again, a grating is used as an example of a coupler / antenna to illustrate this concept).

[0158] Figure 48 This is a perspective view of a dual-grating switch 5000 traveling laterally 5006 with in-plane and out-of-plane stopping orientations relative to waveguide 5012. The substrate has multiple type I switches (e.g., 5010a, 5010b) for guiding light to bus waveguides 5012a, 5012b, 5012c, and 5012d. In this illustration, dual gratings 5014a and 5014b are aligned such that grating 5014a is aligned with bus waveguide 5012a, and gratings 5014a and 5014b are centered between adjacent bus waveguides 5012a and 5012b, such that no light is coupled, or grating 5014b is aligned with bus waveguide 5012b, such that light is coupled.Figure 48 As shown, these MEMS switches 5000 have three orientations: a neutral orientation, where two gratings are located between two waveguides and do not overlap with either of them (both pixels are off, orientation 5014); a grating overlaps with one waveguide (one pixel is on, orientations 1 and 5014a); and a switch 5014a, where one grating overlaps with one waveguide (one pixel is on). Similarly, depending on which pixel will be turned on, the switch will be deflected until it reaches a stop against a mechanical spring (e.g., ...). Figure 48 (A schematic diagram with a single switch is shown). Since the grating is larger than the waveguide, the bouncing effect on performance will be very small. Deflection can be achieved electrostatically, inductively, piezoelectrically, or similarly. However, in this design, a row switch is not necessary because orientation 5014 is a completely closed orientation (neither grating overlaps with either bus waveguide). The waveguides can be connected via a branch tree, and different pixels can be turned on by turning the switch to orientations 5014a and 5014b. In this case, the MEMS switch is a three-way switch. And, of course, the distance between the grating layer and the bus waveguide layer should be small enough to ensure that enough light can couple from the bus waveguide to the grating when the switch is in orientation 5014a or 5014b.

[0159] Figure 49 This is a perspective view of a dual-mode switch 5100 in which the grating 5108 is positioned in a plane. The dual-mode switch 5100 includes a substrate 5102, and suspended above the substrate 5102 is a grating 5108 having a dual-mode piezoelectric actuator 5106 on a suspension layer 5104. When the dual-mode piezoelectric actuator 5106 is activated 5110, the dual-mode switch 5100 moves to... Figure 50 . Figure 50 This is a perspective view of a dual-mode switch 5200 with a vertically rotating grating 5208 in an out-of-plane orientation. The dual-mode switch 5200 includes a substrate 5202, and suspended above the substrate 5202 is a grating 5208 having a dual-mode piezoelectric actuator 5206 on a suspension layer 5204.

[0160] Figure 51 This is a perspective view of a switch array 5300 in which grating elements rotate about an axis perpendicular to the waveguide (e.g., about the x-axis). A substrate 5302 supports bus waveguides 5312a, 5312b, 5312c, and 5312d such that light traveling in direction 5310 can be distributed to each bus waveguide 5312a, 5312b, 5312c, and 5312d. Here, gratings 5316, 5304, and 5314 are configured to rotate 5306 about the x-axis, and when active (e.g., grating 5314), light 5308 is guided from bus waveguide 5312b. Although this is shown as emitting light, it can also be used to receive light. Similarly, Figure 52This is a perspective view of a switch array 5400 in which grating elements rotate about an axis parallel to the waveguide (e.g., about the y-axis). A substrate 5402 supports bus waveguides 5412a, 5412b, 5412c, and 5412d such that light traveling in the direction 5410 can be distributed to each bus waveguide 5412a, 5412b, 5412c, and 5412d. Here, gratings 5416, 5404, and 5414 are configured to rotate 5406 about the y-axis, and when active (e.g., grating 5414), light 5408 is guided from bus waveguide 5412b. Although this is shown as emitting light, it can also be used to receive light.

[0161] MEMS switches can also be designed to be tilted or folded, such as... Figure 51 and Figure 52 As shown. In Figure 51 In this design, the MEMS switch is driven to rotate about the x-axis in the yz plane. When the MEMS switch is parallel to the y-axis, there is overlap between the grating and the bus waveguide, and if the distance between the grating and the waveguide is kept small enough, light can be coupled from the bus waveguide to the grating and further emitted into free space, thus turning on the MEMS switch. Figure 49 When the MEMS switch is tilted to a sufficiently large angle such that the optical coupling is very weak, the MEMS switch is turned off. Figure 50 Similarly, such as Figure 52 As shown, the MEMS switch is driven to rotate about the y-axis in the xz plane. The MEMS switch can be composed of, for example, Figure 49 and Figure 50 The dual piezoelectric chip actuator or electroactive polymer drive shown is illustrated.

[0162] The switch can also rotate in a plane to slide above the waveguide (like a disk gyroscope), instead of just sliding at a 90-degree angle. Figure 53 Similar, but in different proportions. Figure 53 This is a top view of the grating array 5500 on a rotating disk 5502, which utilizes a rotation mechanism for in-plane and out-of-plane alignment. The rotating disk 5502 includes gratings 5504 arranged in an array, such that rotation of the disk 5508 allows the gratings 5504 to align with a bus waveguide 5506 to emit or receive light. One advantage is that the antenna is controlled by only one motor, rather than each antenna being controlled by a switch. The antennas can be designed with a specific pattern that does not affect polarization during rotation.

[0163] Additionally, MEMS switchable gratings can use bistable films to reduce operating power. In this case, MEMS switch actuation can be a combination of two methods to achieve its on or off state. Figure 54AThis is a cross-sectional view of a coupler waveguide 5600 having a bistable membrane 5612 in the closed position. A substrate 5602 supports a bus waveguide 5604, an actuation electrode 5606, and a mechanical stop 5608. On the suspension layer is the bistable membrane 5612, which includes a reactive electrode 5607, a mechanical stop 5608, and a coupler waveguide 5610. Figure 54B This is a cross-sectional view of a coupler waveguide with a bistable 5612 in the open orientation. Figure 54A The switch illustrated in the diagram has a coupler waveguide 5610 (with a grating) on ​​a flexible upper membrane 5612. In the off state, the coupler waveguide 5610 is disconnected from the bus waveguide 5604. To change the switch to the on state, the coupler waveguide 5610 needs to be pulled down. Figure 54B The bus waveguide 5604 is an example. Electrostatic pull-down force applied by electrodes 5606 and 5607 is an actuation method, but this requires a constant current to keep the switch on. This increases the power required to operate the device. To eliminate the need to maintain a constant power application to keep the device on, stress tuning of the membrane can be implemented to create a bistable membrane. This is done by depositing a compressive stress film 5612 onto the top surface of the membrane coupler waveguide 5610. The stress needs to be tuned so that the membrane is parallel to or very slightly bowed compared to the lower surface. This membrane has bistable properties, meaning that it can be flat or slightly bowed in the absence of actuation force and remains on the bottom even when electrostatically pulled down, even when the power applied by electrodes 5606 and 5607 stops. This method allows the switch to be turned on by pulling it down using only a short power pulse and the switch to be kept on by the bistable membrane itself, requiring no power when the switch is on. To return the membrane to the disengaged off state, a pulsed repulsive electrostatic force is used to push the membrane into the disengaged off mode.

[0164] These proposed in-plane MEMS switches can also be organized into arrays and combined with lenses for beam control in optical transmitters, receivers, or transceiver terminals. All switch combination and branch tree combination concepts, as well as row / column wiring concepts, are also applicable to the proposed in-plane MEMS switches.

[0165] Although the entirety of the invention has been illustrated by description of various embodiments, and although these embodiments have been described in considerable detail, the applicant does not intend to limit the scope of the appended claims or in any way to such details. Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details, representative devices and methods, and illustrative examples shown and described. Consequently, deviations from such details may be made without departing from the spirit or scope of the overall inventive concept.

Claims

1. An optical switch, comprising: The first bus waveguide is supported by a substrate; An optical antenna suspended above the first bus waveguide by a spring; as well as Interdigitated electrodes couple the substrate to the optical antenna and are configured to control the orientation of the optical antenna relative to the first bus waveguide. Specifically, when the voltage difference applied to the interdigital electrodes is less than the lower threshold, the optical antenna is in a first position deviating from the first bus waveguide; when the voltage difference applied to the interdigital electrodes is greater than the upper threshold, the optical antenna is in a second position deviating from the first bus waveguide, and the offset at the second position is greater than the offset at the first position.

2. The optical switch according to claim 1, further comprising: A second bus waveguide, supported by a substrate and parallel to the first bus waveguide. Specifically, when the voltage difference applied to the interdigital electrodes is less than the lower threshold, the optical antenna is in a first position that is offset from the first bus waveguide by a first distance; when the voltage difference applied to the interdigital electrodes is greater than the upper threshold, the optical antenna is in a second position that is offset from the second bus waveguide by a second distance.

3. The optical switch according to claim 2, wherein, When a voltage less than the lower threshold voltage difference is applied to the interdigital electrode, the first coupling efficiency between the first bus waveguide and the optical antenna is greater than 50%, and the second coupling efficiency between the second bus waveguide and the optical antenna is less than 1%. When a voltage greater than the upper threshold voltage difference is applied to the interdigital electrode, the first coupling efficiency between the first bus waveguide and the optical antenna is less than 1%, and the second coupling efficiency between the second bus waveguide and the optical antenna is greater than 50%.

4. The optical switch according to claim 1, wherein, The lower threshold voltage difference is 5 volts, and the upper threshold voltage difference is 20 volts.

5. The optical switch according to claim 1, wherein, The substrate is a silicon-on-insulator (SoI) substrate, and the bus waveguide is etched in the silicon layer of the substrate coupled to the insulating layer.

6. The optical switch according to claim 1, wherein it is arranged in an optical switch array, wherein, An optical antenna is an optical antenna array arranged in at least two columns separated by a gap, and the optical antenna array is arranged in at least one row such that a first orientation and a second orientation separate the gap.

7. The optical switch according to claim 6, further comprising: An optical tree configured to distribute light to an optical antenna array, the optical tree being configured to selectively enable at least one row of a row.

8. An optical switch, comprising: Bus waveguide supported by a substrate; An optical antenna suspended above the bus waveguide by a spring; as well as Interdigitated electrodes couple the substrate to the optical antenna and are configured to control the orientation of the optical antenna relative to the bus waveguide. When the voltage difference applied to the interdigitated electrodes is less than a lower threshold, the optical antenna is positioned at a first orientation relative to the bus waveguide. When the voltage difference applied to the interdigitated electrodes is greater than an upper threshold, the optical antenna is positioned at a second orientation relative to the bus waveguide. The first orientation and the second orientation are separated by a predetermined distance.

9. The optical switch according to claim 8, wherein, When the optical antenna is in the first and second orientations, the coupling efficiency between the bus waveguide and the optical antenna is greater than 50%.

10. The optical switch according to claim 9, wherein it is arranged in an optical switch array, wherein, An optical antenna is an array of optical antennas arranged in at least two rows and at least one column spaced apart by a gap, such that a first orientation is separated from the gap by a second orientation.

11. The optical switch according to claim 10, further comprising: An optical tree configured to distribute light to an optical antenna array, wherein the optical antenna array is arranged in at least one row and at least one column, and the optical tree is configured to selectively enable one row of at least one row.

12. The optical switch according to claim 10, further comprising: An optical tree configured to collect light from an optical antenna array, wherein the optical antenna array is arranged in at least two rows and at least one column, and the optical tree is configured to selectively enable at least one row of a row.

13. The optical switch according to claim 10, further comprising: A lens spaced apart from a substrate and configured to diffract light onto an optical antenna, wherein the lens is configured to translate along a vector perpendicular to the substrate, and the distance between the lens and the substrate changes as the lens translates along the vector.

14. The optical switch according to claim 10, further comprising: A lens spaced apart from a substrate and configured to diffract light onto an optical antenna, wherein the substrate is configured to translate along a vector perpendicular to the lens, and the distance between the substrate and the lens changes as the substrate translates along the vector.

15. The optical switch according to claim 10, wherein, When the voltage difference applied to the interdigitated electrodes is between the lower threshold and the upper threshold, the coupling efficiency is greater than 50%.

16. A beam control system, comprising: Bus waveguide supported by a substrate; An optical antenna supported by a spring at a distance above the bus waveguide; Interdigitated electrodes couple the substrate to the optical antenna and are configured to control the orientation of the optical antenna relative to the bus waveguide. An optical tree having at least one type of optical switch, the optical tree being configured to collect light from an optical antenna; as well as A lens, spaced apart from the substrate, is configured to diffract light onto an optical antenna. Specifically, when the voltage difference applied to the interdigital electrodes is less than the lower threshold, the optical antenna is positioned at a first distance away from the bus waveguide; when the voltage difference applied to the interdigital electrodes is greater than the upper threshold, the optical antenna is positioned at a second distance away from the bus waveguide, and the second distance is less than the first distance.

17. The beam control system according to claim 16, wherein, The optical antenna is an array of optical antennas arranged in at least one row and at least one column, and the optical tree is configured to selectively enable one row of at least one row.

18. The beam control system according to claim 16, wherein, The optical antenna is an array of optical antennas arranged in at least one row and at least one column, and the optical tree is configured to selectively enable one of the columns.

19. The beam control system according to claim 16, wherein, The lens is configured to translate along a vector perpendicular to the substrate, and as the lens translates along the vector, the distance between the lens and the substrate is changed.

20. The beam control system according to claim 19, wherein, An optical antenna is a two-dimensional grating that provides a Gaussian beam spot in the far field, and the Gaussian beam spot is focused onto the optical antenna as the lens is translated along the vector.

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